Here’s More Evidence That Using Just One Egg in IVF Is Better

Anyone considering in vitro fertilization may think that it’s best to insert two or even three fertilized embryos, but more and more doctors are advising they use just one.

Transferring multiple embryos during IVF cycles has led to a direct increase in births of multiples (twins, triplets, or more) in the United States. In 2013, 41 percent of IVF deliveries were multiples. Some clinics push this in order to boost their pregnancy rates, the New York Times reports, but it’s not risk-free. Twins and triplets can be a blessing, but multiples can also increase the likelihood of complications for mothers and their babies including miscarriage, preeclampsia, premature labor, cesarean section, and prolonged hospitalization.

The American College of Obstetricians and Gynecologists said in August that transferring one embryo at a time can result in high pregnancy rates while drastically reducing the number of multiples. (It doesn’t eliminate the risk as some embryos will divide in half on their own, resulting in identical twins.)

A study out this month in the journal Fertility and Sterility supports this recommendation. A research team looked at 2013 data from the 467 IVF clinics in the United States — which are required to report outcomes to federal officials — and found that transferring a single embryo in women 37 and younger resulted in a reduction in multiple birthrates but not overall birthrates. There were roughly the same number of births, just with fewer twins and triplets.